Apparatus for pulverizing vulcanized rubber and rubber products

ABSTRACT

An apparatus for pulverizing vulcanized rubber and rubber products includes an ovoid rotor housed within a casing whereupon during rotation of the rotor, and/or the casing, the rubber material is subjected to various cutting and shearing forces. Additional means may be provided for periodically altering the clearance between the rotor and casing whereby the grinding effects can be enhanced, and still further means may be utilized to alter the clearance in a different manner whereby in addition to being subjected to cutting and shearing forces the material also undergoes a crushing operation.

United States Patent Sawa l l June 17, 1975 [54] APPARATUS FORPULVERIZING l,762,368 6/[930 Van Dergrift 241/67 E D R BEER 2,466.4434/l949 Klaassen 24l/22l X RUBB R AN U 3,664,592 5/1972 Schweigert ct all241/73 3,680.79) 8/1972 Hallerback v. 24l/67 X [75] Inventor: KlyohlkoSawa, Kobe, Japan FOREIGN PATENTS OR APPUCATIONS Assignee: Kobe Steel.Kobe Japan l,2()b 886 2/l960 France .1 241/228 [22] Filed: Apr. 2, 1973A Prtmary Examiner-Roy Lake l pp 346.871 Assistant Examiner-Howard N.Goldberg Attorney, Agent, or Firm-Oblon. Fisher. Spivak, {30] ForeignApplication Priority Data Mcclenand Augt l4, l972 Japan 7. 4181286 Augl4, I972 Japan 4781287 [57] TR Aug 23 972 Japan n 4184753 An apparatusfor pulverizing vulcani zed rubber and rubber products includes an ovoidrotor housed within 52 us. (:1. 241/228; 241/67; 241 m; a casingwhereupon during rmativn of the rotor 241/227; 241/231; 241/241 /or thecasing, the rubber material is subjected to vari- [511 Int. Cl. B02C13/02 OHS Cutting and Shearing forces- Additional means y [58] Field ofsearch241/67, 73 221, 222, be provided for periodically altering theclearance be- 241/239 24] tween the rotor and casing whereby thegrinding effects can be enhanced, and still further means may be [56]References Cited utilized to alter the clearance in a different mannerUNITED STATES PATENTS whereby in addition to being subjected to cuttingand shearing forces the material also undergoes a crushing 373,342l1/l887 Cornelius 24l/222 X Operation. 760,010 5/l904 Montgomery.24l/228 UX l,428.687 9/1922 Ferencz 241/228 X 2 Claims, 20 DrawingFigures PATENTEDJUH 11 1975 3 3 SHEET 1 PATENTEDJUN 1 1 875 .889.889

FIG. I

PATENTEDJUN17 1915 3,889,889

SHEET PATENTEDJUN 17 ms SHEET ||..l fi J mm? a: m 3* mm: 03 Q: E: m m38r Q: N 0 5 1 w? H/ R m? a: i m; x x g E. 5 L J r K i naasmes PATENTEI]JUN 1 7 I975 SHEET 1 APPARATUS FOR PULVERIZING VULCANIZED RUBBER ANDRUBBER PRODUCTS BACKGROUND OF THE INVENTION l. Field of the InventionThe present invention relates generally to a pulverizing apparatus andmore particularly to an apparatus for pulverizing vulcanized rubber andrubber products.

2. Description of the Prior Art Vulcanized rubber and rubber productshave heretofore been pulverized or ground by means of a grinder of theimpact type, a reciprocating shearing machine or a cracking roll. Sincearticles of this kind are characterized by a high degree of elasticityand often comprise fibers or other reinforcing means incorporatedtherein, even when they are subjected to the action of a grinder of theimpact type, the grinding efficiency is very low whereby the articlesare merely torn into strips and the like which are quite irregualr insize.

In the instance of a reciprocating shearing machine, the articles areuniformly cut into small pieces, but the grinding efficiency is alsoextremely low, and even with the use of such a shearing machine of thistype, it is relatively impossible to pulverize these articles intoparticles or granules. Accordingly, the pieces withdrawn from theshearing machine must be subjected to a postshearing treatment by meansofa grinding roll. Furthermore, in the instance of a cracking roll, itis also necessary to effect such post-grinding treatment with use of agrinding roll, and thus, the conventional techniques have seriousproduction drawbacks.

SUMMARY OF THE INVENTION Accordingly, it is an object of the presentinvention to provide an improved pulverizing apparatus.

Another object of the present invention is to provide an improvedpulverizing apparatus which does not experience the drawbacks ofconventional apparatus.

Still another object of the present invention is to provide an improvedpulverizing apparatus which can be utilized to easily pulverizevulcanized rubber and rubber products.

Yet another object of the present invention is to provide an improvedpulverizing apparatus which can be utilized to pulverize vulcanizedrubber and rubber products while expending less power than normallyrequired utilizing conventional techniques.

It is a further object of the present invention to provide an improvedpulverizing apparatus exhibiting a substantially high degree ofefficiency.

A yet further object of the present invention is to provide an improvedpulverizing apparatus which can effectively pulverize vulcanized rubberand rubber products into particles of uniform size.

A still further object of the present invention is to provide animproved pulverizing apparatus which can effectively pulverizevulcanized rubber and rubber products into particles having any one of aplurality of predetermined sizes.

A yet still further object of the present invention is to provide animproved pulverizing apparatus wherein the material to be pulverized issubjected to variable frictional cutting, shearing, and crushing forces.

As a result of our research work conducted with the view towardproviding a novel apparatus for pulverizing vulcanized rubber and rubberproducts, especially used rubber tires and rubber belts, amounts ofwhich have been currently increasing greatly, which can overcome theforegoing defects of convenional techniques and which can pulverizethese vulcanized rubber articles assuredly with high degree ofefficiency, in accordance with this invention, there is provided anappara tus for pulverizing vulcanized rubber or rubber products, whichpacks a vulcanized rubber or rubber product between a rotor having anegg-shaped cross-section and a casing surrounding the rotor, and rotatesthe rotor relative to the casing to thereby impose upon the rubbermaterial frictional forces due to frictional forces between the rubbermaterial and the rotor and between the rubber material and the casing aswell as shearing forces within the interior of the rubber material.

In a preferred embodiment of this invention for accomplishing thepulverization more effectively, a vulcanized rubber or rubber productmay be packed between a rotor having an egg-shaped cross-section and acasing surrounding this rotor, and the rubber material is subjected tofrictional forces due to such forces between the rubber material and therotor and between the rubber material and the casing and also toshearing forces within the interior of the rubber material, by rotatingthe rotor relative to the casing and simultaneously changing theclearance formed between the outer periphery of the rotor and the innerwall of the casing.

According to this invention, pre-treatment required prior to thepulverization is extremely simple, and pulverization can be accomplishedat a high rate of efficiency and the handling of the pulverized productsis quite easy. More specifically, even a rubber material of a largedimension can be pulverized conveniently, and if the metal wiresconstituting the bead portions of tires have been removed in advance,reinforing means, such as fibers, do in fact separate from thevulcanized rubber articles when they are pulverized into fine particlesand these reinforcing means retain their fibrous form so as to be easilyseparable from the other pulverized products by means of a sievingscreen or the like, whereupon the pulverized rubber products may beapplied to a predetermined use while the fibrous products are easilydisposed of by combustion or the like.

An apparatus for practicing this invention effectively comprises a rotorhaving an egg-shaped cross-section, a casing surrounding the rotor, adrive mechanism for rotating the rotor relative to the casing, and aclearance-changing mechanism adapted to change the clearance formedbetween the outer periphery of the rotor and the inner wall of thecasing as the rotor rotates.

The clearance-changing mechanism is effective for imposing upon thepacked vulcanized rubber or rubber product frictional forces due to suchforces between the rubber material and the rotor and between the rubbermaterial and the casing, and also shearing forces within the interiorofthe rubber material. Furthermore, this mechanism is effective forreducing the power required for pulverization.

As an effective clearance-changing mechanism, the casing may have aninner wall of non-circular crosssection, such as for example, convex andconcave portions upon the surface of the inner wall, or a casing havingan inner wall of circular cross-section, the center of which differsfrom the rotational axis of the rotor. As a more effectiveclearance-changing mechanism, there may also be employed a casing havinga conical inner wall wherein the casing is capable of axial reciprocablemovement, or a casing having side wall sections which are capable ofradial expansion and contraction. By providing such mechanism, cutting,shearing and crushing forces can be imposed upon the packed vulcanizedrubber or rubber product regardless of the configuration and sizethereof, and hence, effective pulverization can be attained.

In order to effectively impose such forces upon a packed rubber materialsuch as vulcanized rubbers and rubber products, it is also possible toutilize a drive mechanism for rotating both the rotor and the casing, ora mechanism for rotating the casing in a direction opposite to thedirection of rotation of the rotor. By provision of such mechanisms, itis possible to prevent a non-uniform distribution of the packed rubbermaterial within the casing caused by any deviation in weight of theparticles, and therefore, pulverization can be accomplished uniformlythroughout the entire extent of the rotor.

BRIEF DESCRIPTION OF THE DRAWINGS Various other objects, features, andattendant advantages of the present invention will be more fullyappreciated as the same becomes better understood from the followingdetailed description when considered in connection with the accompanyingdrawings, in which like reference characters designate like orcorresponding parts throughout the several views, and wherein:

FIG. 1 is a cross-section view of a pulverizing apparatus constructedaccording to this invention and showing its cooperative components;

FIG. 2 is a side elevation view, partly in section, of the apparatusshown in FIG. I;

FIG. 3 is a cross-section view of another embodiment of a pulverizingapparatus constructed according to this invention and showing itscooperative components;

FIG. 4 is a cross-section view of still another embodiment of apulverizing apparatus constructed according to this invention andshowing its cooperative parts, wherein the rotor casing is axiallyreciprocable',

FIGS. 5, 6 and 7 are cross section views taken along the lines IIII,IIIII| and IVIV of FIG. 4;

FIG. 8 is a view similar to that of FIG. 4 illustrating still anotherembodiment of the present invention wherein wall sections within therotor casing are radi' ally expansible and contractible;

FIGS. 9, l and 11 are cross-section views taken along the lines VV,VI-VI and VIIVII of FIG. 8;

FIG. 12 is a cross-section view illustrating a casing of the presentapparatus which includes a clearancechanging mechanism;

FIGS. 13 and 14 are views similar to that of FIG. 12 illustrating otherembodiments of rotor and casing clearancechanging mechanisms;

FIG. 15 is a cross-section view of a further embodiment of the presentinvention in which a drive mechanism rotates the rotor casing in adirection opposite to the direction of rotation of the rotor;

FIG. 16 is a view similar to that of FIG. 15 wherein the rotor and rotorcasing are eccentrically located relative to one another; and

FIGS. 17-20 are cross-section views of the apparatus shown in FIG. 16illustrating the relative positions of the rotor and rotor casing atone-fourth revolution intervals.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to thedrawings and more particularly to FIGS. 1 and 2 thereof, a substantiallyovoid or eggshaped rotor l is rotatably supported within the end walls 3of a substantially circular casing 2 through means of a bearing 4whereby a clearance d exists between the rotor and easing due to thefact that the journal portion 5 of rotor l is eccentrically supportedrelative to the casing 2, the distance between the axes of rotor l andcasing 2 being denoted h. The casing 2 is composed of substantially halfsections bonded together, one sectional member 2' being supported upon abase 6 by means of legs 7 and including a vertically extending chute orhopper 8 for the deposition of material to be pulverized. The othersectional member 2" is hinged to the first sectional member 2' and is soconstructed that it can be opened by means of piston and cylinderdevices 9 also supported upon base 6. A ram 10 is reciprocably mountedwithin the chute 8 so as to press a material M to be pulverized into thecasing 2, whereby the pulverized product may be withdrawn from anotherchute 11 disposed below casing 2.

Referring now to FIG. 3 another embodiment of the present invention isdisclosed in which two ovoid rotors 22 are employed, the substantiallycircular rotor cas ings 21 being connected together at a plane locatedequidistantly from each of the rotor axes. A material M to be pulverizedis introduced through a vertically extending chute or hopper 8 centrallydisposed atop the casings 21 under the influence of a press ram 10 movable within chute 8 and the pulverized product is with drawn from a lidmember 23 which is disposed within a lower central portion of thecasings, and which is ro tatable in the direction indicated by the arrowabout a fulcrum shaft 24. Rotors 22 are angularly positioned within thecasings 21 such that a phase difference of exists therebetween, thejournal portions of the rotors being supported within the end walls ofthe casings in a manner similar to that of FIG. 1, and they are rotatedin opposite directions through means of a syn-- chronizing device, notshown, such as for example, appropriate gearing, the chain lines 26generally indicating the locus attained by the rotors relative to thecas ings as the rotors are rotated. In the instance that fine holes 27are employed within the lid member 23, such holes render lid 23 a sievewhereby the pulverization process can be conducted in a continuousmanner.

During the course of research, one experiment involved the utilizationof apparatus such as that shown in FIG. 3 whereby rubber tires werepulverized. The distance d between the rotors 22 and the casings 21 wasadjusted to 2.4 mm, the diametrical dimension H of the rotor 22 was 204mm, and the rotational speed of the rotors 22 was 62 rpm. A rubber tireM was initially subjectedto a pre-pulverization treatment whereby theconventional meta] wires were removed from the bead portions and thetire was subsequently cut into blocks having a volume of approximately3000 cm, such as for example, 20 cm in length, 20 cm in width, and 7 cmin thickness. Approximately kg of such blocks were then pressed into thecasings 21 by means of a ram 10, and within 60 seconds, the blocks werefinely pulverized to particles having an average size of 60 mesh. Whenthe pulverization was continued for a duration of seconds, the resultingparticles had a size of approximately 100 mesh with no substantialdeviation or irregularity in particle size. Fibers utilized asreinforcers were also obtained in strips having an average length of 50mm and were easily separable from the pulverized rubber product by meansof a sieving screen or the like.

As is seen from the foregoing, according to this invention, a vulcanizedrubber article. pulverization of which has heretofore been verydifficult or relatively and economically impossible according toconventional techniques, can easily be pulverized into fine particles ata high rate of efficiency. In view of the ex pected increase in use ofarticles of vulcanized rubber, this invention can be said to make greatcontributions to the art.

In order to be able to vary or adjust the size of the pulverized productparticles as desired, the relative clearance between the rotors and thecasings must be alterable, and consequently, a clearance-changingmechanism may be employed which comprises a casing having a conicalinner wall portion and a rotor disposed within the casing wherebyfurther means are employed to axially reciprocate the casing relative tothe rotor, the clearance between the rotor and the conical wall portionthereby being adjusted as desired.

As is illustrated in FIGS. 4-7, a rotor shaft 201 provided with a feedscrew portion 202 and a grinding rotor blade portion 203 is disposedwithin a longitudinal, horzontally disposed casing 204 having avertically extending material inlet 205 at one end and a radiallyextending outlet 206 at the other end. A base 207 supports a drivinggear 208 which is actuated by means of a motor, not shown, so as to inturn drive the rotor shaft 201 through several reduction gears. In thismanner, material entering inlet 205 is continuously fed by means ofscrew 202 from the screw chamber 211 into a grinding chamber 212 havingthe egg-shaped grinding rotor blade 203 disposed therein, both endsofthe rotor shaft 201 being rotatably supported upon hearing stands 209and 209' via bearings 210 and 210'. The thrust load generated at thefeed screw portion 202 is released by means of a thrust pad or bearing210.

The inner wall of the grinding chamber 212, as well as the rotor blade203 is formed so as to have a tapered configuration so that the chippedclearance L between the chamber and blade at the inlet portion isgreater than the chipped clearance L between the chamber and blade atthe outlet portion. A radial protrusion 213 is provided upon theexterior portion of the casing 204 so as to be interengaged with one endof a piston rod of a hydraulic piston and cylinder device 214 mountedupon base 207 whereby the casing 204 may be reciprocably moved in thehorizontal direction by appropriate operation of device 214 so as tothereby adjust the chipped clearance within the grinding chamber inorder to satisfy the requirement of L L A safety valve 215 may bemounted within the hydraulic circuit associated with the hydraulicdevice 214 so as to compensate for any overload brought about by theincorporation of different matter or the like.

In this manner then when material to be ground, such as for example,vulcanized rubber or rubber product, is charged from the inlet 205 andthe rotor shaft 201 is rotated, the material is continuously fed fromthe screw chamber 211 to the grinding chamber wherein it is cut intoparticles of a size corresponding to the chipped clearance between thegrinding rotor blade 203 and the inner wall of the grinding chamber 212while undergoing cutting and shearing forces within the grinding chamber212, whereupon the ground material is ultimately withdrawn from theoutlet 206. Since the chipped clearance L, at the inlet portion isgreater than the chipped clearance L at the outlet portion, the materialis coarsely ground within the inlet portion of the grinding chamber 212whereby the resulting particles are of a relatively large sizecorresponding to the chipped clearance L at the initial stage, and asthe material moves toward the outlet end of the casing, it is graduallyground to a size which corresponds to the chipped clearance L Thus, atthe final stage the material is ground into particles having a diametercorresponding to the chipped clearance L adjacent to the outlet portion206 of the grinding chamber 212 whereby the same may be recovered fromthe outlet 206 in the form of a finely divided product having apredetermined size.

It may thus be appreciated that if the position of the casing 204 ismoved in the horizontal direction toward the right or left by means ofthe hydraulic cylinder 214, the chipped clearances are changed and theparticle size of the ground product can consequently be adjusted as maybe desired. Accordingly, it is possible to obtain a ground producthaving a desired particle size. It will be further appreciated that asthe chipped clearance at the inlet portion is greater than the chippedclearance at the outlet portion, the load imposed upon the rotor shaftat the initial stage of grinding can be diminished due to the fact thatthe material is not ground to a desired size within one step of theprocess, but on the contrary, such is gradually and successively groundto a smaller size along the entire length of the rotor blade. Therefore,the grinding operation can be conducted uniformly throughout the entireapparatus and the grinding efficiency increased while the occurrence oflocal abrasion or heat generation prevented, the result being that arubber material can be ground to a prescribed size smoothly and easilyat a relatively low expense of power with a substantial decrease in thepossibility of encountering mechanical disorders in the apparatus.

In addition, the limitation upon the amount or size of the chargedrubber material is effectively obviated for even when material ofarelatively large size is charged into the apparatus, it can be graduallyground to a smaller size due to the gradual decrease in the chippedclearance and finally to a finely divided product of a prescribed sizewith the sole use of the apparatus of the present invention. Inaccordance with this invention, there is thus provided a grindingapparatus especially suitable for grinding a highly elastic vulcanizedrubber or vulcanized rubber product, the grinding operation beingeffectively independent of the size of the charged material.

While the clearance-changing mechanism disclosed in FIGS. 47 included anaxially reciprocable casing, the clearance-changing mechanism may alsocomprise a casing having side walls capable of movement in the radialdirection as shown in FIGS. 8-11. The apparatus of this embodimentincludes a base 301, a substantially cylindrical horizontally disposedrotor casing 304 provided with a vertically extending inlet 302 at oneend for feeding rubber material into the casing and a vertical, radiallyextending outlet 303 at the other end for discharging a ground productand a rotor shaft 307 longitudinally disposed within casing 304 having afeed screw portion 305 adjacent the casing inlet and an ovoid grindingrotor portion 306 adjacent the outlet, a driving motor, not shown, andreduction gearing 308 being additionally provided to impart rotarymotion to the shaft. The motor and gearing 308 are mounted upon the base301 and serve to rotate another shaft 311 through means of anintermediate gear 309 and a small gear 310 associated with shaft 311. Aswill be apparent hereinafter, the apparatus is so constructed that thegrinding chamber 317 in which grinding rotor 306 is disposed may beradially enlarged and contracted by means of the rotation of rotaryshaft 311. Casing 304 of course also comprises a feed screw chamber 316which houses the feed screw portion 305 and the casing 304 isappropriately supported upon base 301. The ends of the rotor shaft 307are rotatably mounted within bearings 314 and 314', and 315 and 315,respectively provided within a bearing stand 312 and a gear box 313, thelatter serving to also house the gearing 308, a thrust load generated atthe feed screw portion 305 being compensated for by means of the thrustbearing 315.

Referring now to FIGS. 911, the particular construction ofthe grindingchamber 317 is illustrated, the interior portion of the casing 304corresponding to the grinding chamber 317 being so formed as to have asquare cross-section while a plurality of pivotable wall sections aredisposed within the square casing section. The pivotable wallsectionsare serially arranged in three groups, each group having fourwall sections, such as, for example, 318a-318d, 3190-319d, and320a-320d. The exterior portions of each wall section conforms to therespective squared interior portion of the casing 304 while the interiorportions of the wall sections are arch-shaped whereby chipped clearancesL L and L are respectively formed between the outer periphery ofthegrinding rotor blade 306 and the arch-like inner faces 321a'321d,322a-322d, and 3230-323d. Each of the side wall sections arerespectively interlocked with pinions 3240-324d, 325a325d, and 3260-326drotatably supported within casing 304 through means of eccentric shafts327a327d, 3280-32811, and 329a-329d which support the pinions,connecting links 330a-330d, 3310-3314, and 332a-332d, and pins3330-333d, 334a-334d, and 335a-335d which support the wall sections.

The pinions are respectively engaged with teeth 339, 340 and 341disposed upon the interior surfaces of ring gears 336, 337, and 338which are rotatably supported upon the outer periphery of the casing304. Gears 345, 346, and 347 fixed to the rotary shaft 311 respectivelyengage teeth 342, 343 and 344 disposed upon the exterior surfaces of thering gears 336, 337 and 338, and when the pinions are rotated throughrotation of shaft 311, gears 345, 346 and 347, and ring gears 336, 337and 338, all of the eccentric shafts 327a327a', 3280-32811, and329a-329d cause a crank movement to be imparted to the side wallsections at a stroke equal to twice the eccentric radius, whereby thechambers defined by the side wall sections may be continuously expandedor contracted.

When a rubber material to be ground is deposited within the inlet 302and the rotor shaft 307 is rotated, the material is continuously fedfrom the feed screw chamber 316 into the grinding chamber 317 by meansof the feed screw 305 whereby the material is gradually and successivelyground to a prescribed size, following which the ground material isdischarged form the outlet 303. While within the grinding chamber 317,not only are cutting and shearing operations performed by means of thegrinding rotor blade 306 and the inner wall of the grinding chamber 317but a crushing operation is also performed. More specifically, therotary shaft 311 is rotated coincidentally with the rotor shaft 307 anddue to the rotation of the rotary shaft 311, the side walls 318a-318d,319a319d, and 320a-320d are actuated through means of theabove-mentioned gears, ring gears, pinions and links, whereby thearch-like inner surfaces 321a321d, 322a-322d, and 323a-323d ofthe sidewalls are in turn actuated so as to repeatedly expand and contract thechambers in a radial direction relative to the grinding rotor blade 306whereupon a crushing operation is accomplished between the grind ingrotor blade 306 and the arch-like inner surfaces of the side walls.Thus, the material fed to the grinding chamber undergoes crushing,cutting and shearing forces within the grinding chamber 317 and isgradually ground to a size corresponding to the final predeterminedchipped clearance.

It is possible to employ only one set of side wall sections foraccomplishing the aforementioned grinding and crushing operationswhereby the entire inner wall defining the grinding chamber may beuniformly expanded and contracted. In the embodiment illustrated inFlGS. 8-11, three groups of side wall sections have of course betweenemployed, and the lengths of the links are so set that the chippedclearance L between the group of wall sections positioned at the inletside of the grinding chamber and the rotor blade is greater than thechipped clearances L and L between the respective groups of wallsections positioned toward the outlet side of the grinding chamber andthe rotor blade so as to establish the relation whereby L, L L Byadopting such structure, the rubber material fed into the grindingchamber 317 undergoes crushing, cutting and shearing forces graduallyand successively by each group of side walls, and is ground in astepwise manner while its size is being gradually diminished.Accordingly, it is possible to prevent an extreme load from beingimposed directly upon the rotor shaft 307, and the work of grinding isuniformly distributed along the entire longitudinal extent of thegrinding rotor blade 306 whereby the grinding operation can beaccomplished at a high degree of efficiency.

In conjunction with another preferred embodiment of the presentinvention within any two adjacent groups of side wall sections thelengths of the links may be predetermined such that the inner diameterof the grinding chamber defined by the side wall sections of the groupupon the outlet side when the same are expanded is equal to the innerdiameter ofthe grinding chamber defined by the side wall sections of thegroup upon the inlet side when the same are contracted, and theeccentric phases of the pinions may be so set that the side wallsections of the two adjacent groups move in directions opposite to eachother. Hence, during one cycle of expansion and contraction, the sidewall sections of the two adjacent groups attain the same diameter andtherefore, the rubber material is transported smoothly withoutstagnation and as it is finely ground, it is gradually forwarded towardthe outlet by means of leads mounted upon the rotor blade. In short, thegrinding operation can be accomplished very smoothly if the chippedclearance between the side wall sections of the group nearest to theoutlet and the rotor blade is predetermined according to the desiredsize of the ground particles and the length of the links of each of theother groups of wall sections is determined by adding the radialdistance through which each of the wall sections of the group adjoiningthe group nearest to the outlet moves to the inner diameter of the wallof such adjoining group.

As a result of the above-described structure, the present inventionmakes it possible to repeat crushing, cutting and shearing operations byutilizing only one apparatus and therefore, according to this inventionthe grinding can be accomplished very effectively. Furthermore, sincethe walls of the grinding chamber are periodically expanded andcontracted, stagnation of the rubber material between the rotor bladeand the walls defining the grinding chamber can be completely prevented,with the result that the occurrence of local abrasion or heat generationis not brought about and no excessive load is imposed upon the rotorshaft. Accordingly, even a vulcanized rubber or rubber product having ahigh degree of elasticity can be smoothly and eas' ily ground at a highrate of efficiency for a short time in the apparatus of this invention.

Referring now to FIGS. l220, there are disclosed several aspects orfeatures of the present invention wherein a clearance-changing mechanismis provided such that the clearance between the outer periphery of therotor and the inner walls of the casing may be altered one or more timesduring one rotation of the rotor. In accordance with one aspect of thisembodiment there is provided an apparatus for grinding vulcanizedrubber, vulcanized rubber products and the like, whrein a movable casingportion encompasses only the grinding rotor blade portion of the rotorshaft so as to define a grinding chamber which is rotatably supportedindependently of the other fixed casing portion surrounding the feedscrew whereby the shaft and the movable casing are rotated in such arelationship that the chipped clearance formed within the grindingchamber is thereby changed and consequently, the rubber material isground while undergoing crushing, cutting and shearing forces betweenthe rotor shaft and the movable casing.

In accordance with another aspect of this embodiment, there is provideda grinding apparatus as set forth above, wherein a suitable number ofconcave portions are formed upon the inner wall of the movable casingand the movable casing is rotated at a rotational frequency differingfrom that of the rotor shaft so as to thereby change the chippedclearance formed therebetween. Still further, the movable casing may beeccentrically rotated relative to the rotor shaft whereby the chippedclearance formed therebetween is periodically altered during rotation ofthe same.

As mentioned heretofore, the grinding apparatus of this invention ischaracterized in that the chipped clearance may be altered one or moretimes during one rotation of the rotor shaft. Means such as is shown inFIGS. 12-14 may be considered to be effective for attaining suchalteration of the chipped clearance. In the mechanism illustrated inFIG. 12, one or more concave por tions 414 may be provided within casingportion 413 which houses grinding rotor blade 411 therein and definesgrinding chamber 412 therearound. Simultaneously with the rotation ofthe rotor blade 411, in a given direction, the casing portion 413 isrotated in an opposite direction, and in addition, may be rotated at aspeed different from that of rotor 41].

Thus, the chipped clearance is altered one or more times during onerotation of the rotor blade 4]], the different clearances beingdesignated as L and L as seen in FIG. 12. Even in the instance that arubber article becomes elastically deformed so as to have a wedge-likeform as when it is caught between the rotor blade 41] and the inner faceof the casing 413, such configuration of the material may be immediatelyand automatically changed due to a change in the chipped clearancewhereupon the material may be interposed between the rotor blade and thecasing wall at a differ ent relative position whereby it will undergocutting or shearing forces. As is seen from FIG. 12, upon both sides ofthe rotor blade 411 the relative configuration of the crescent-shapedgrinding chamber 412 is continuously varied during the rotational cyclesand the rubber material therefore also undergoes crushing forces causedby such variation in the grinding chamber volume. Furthermore, therubber material can move freely within the grinding chamber and it istherefore possible to prevent the occurrence of the undesired phenomenonthat the rubber material experiences frictional contact with the wall ofthe grinding chamber for an extended period oftime whereby the materialwill remain stationary within the chipped clearance and the grindingchamber, and thus, the grinding can be accomplished at a high rate ofefficiency.

The above-mentioned effects can be further increased when the concaveportions 414 formed upon the inner face of the casing 413 are such as tohave a configuration such as is shown at 414' in FIG. 13. Morespecifically, a shoulder portion 415 is formed adjacent to the concaveportion 414' in such a manner that the shoulder 415 cooperates with therotor blade 41] whereby the rubber material is subjected to a positivecutting action when caught between the head of the rotor blade 411 andthe shoulder portion 415, and in addition it also undergoes a rollingforce. Thus, the movement of the material is enhanced while the grindingefficiency is further improved.

As is apparent from the apparatus illustrated in FIG. 14, the rotationalaxis O of the rotor blade 41] is eccentrically located relative to therotation axis 0 of the casing 413 by a distance a and consequently asrotational motion is imparted to the apparatus, the chipped clearancebetween the rotor blade and casing will be periodically changed and itis possible to attain an effect quite similar to those effects attainedby utilizing the foregoing apparatus.

As a result of experiments it was confirmed that when vulcanized rubberor vulcanized rubber products are ground within any one of the foregoingapparatus, the above-mentioned deficiencies of conventional apparatuscan be overcome and the grinding efficiency can be greatly improved oversuch conventional apparatus.

Preferred embodiments of apparatus of this invention employing the rotorand casing structure of FIGS. 12-14 will now be illustrated by referenceto FIGS. l520. Referring particularly to FIG. 15, the apparatus of thisinvention comprises a driving member, such as for example, a motor 416and reduction gearing, a substantially cylindrical casing 418 providedwith an inlet 417 for charging rubber material to be ground, and arotatable casing 413 and a rotor shaft 419 interconnected with thereduction gearing. The rotor shaft 419 extends throughout the fixed androtatable casings and includes a feed screw 422 disposed within casing418 and a rotor blade 41] disposed within casing 413. The rotatablecasing 413, as well as the rotor shaft are of course rotatably supportedwithin various bearing members, including a forward bearing stand 420,which are in turn supported by means ofa bed 421, while the fixed casingis supported upon an upstanding gearing housing 423.

The rotor shaft 419 is driven by means of the motor 416, a first pulley424 associated with motor 416, a second pulley 426 which is connected topulley 424 through means of a belt 425, and various gears 427, 428, 429,and 430 disposed within gearing housing 423. A coolant passageway 43]extends axially within the rotor shaft 419 and is supplied with acoolant, such as for example, water, by means of a water supply tube432, cooling water thus being supplied and discharged to the rotor shaftby means of a rotary joint 433 mounted at the front end of the rotorshaft. A hopper, not shown, is provided upon the material inlet 417 ofthe casing 418 for the deposition therein of material to be ground,while the ground rubber material is withdrawn through a radial dischargeoutlet 445. A gear 434 is fixed to, or integral with a peripheralportion of the movable casing 413, and the movable casing 413 is thusinterlocked with gear 428 through means ofa gear 435 engaging gear 434,a shaft 436 associated with gear 435, and gears 437 and 438, gear 438being co-axial with gear 428. In this manner, the construction is suchthat the casing 413 can rotate in a direction opposite to that directionof rotation of the rotor shaft 419.

The rotatable casing 413 has concentric portions and interposedtherebetween is an annular water jacket 439 for cooling purposes. Supplyand discharge of the water to and from the water jacket 439 areaccomplished by means of a water supply tube 440 and a water dischargepipe 44] fixed upon bed 421. The water supply tube 440 and waterdischarge pipe 441 are respectively connected to a radial water supplypassage 442 and a radial water discharge passage 443 which are providedat opposite ends of the water jacket 439, such being sealed by means ofO-rings or packings 444.

Within the grinding chamber, the chipped clearance may be altered as therotor shaft 419 is rotated by adopting any one of the structuresillustrated in the FIGS. 1214, whereby crushing forces, as well ascutting and shearing forces, are imposed upon the rubber material, andthe intended object of this invention, i.e,, conducting a grindingoperation at a high rate of efficiency, can be attained. In the instancethat the chipped clearance is altered by eccentrically locating the axisof rotation 01 of the rotor blade 411 relative to the axis of rotation02 of the movable casing 413 as illustrated in FIG. 14, an apparatussuch as illustrated in FIG. 16 is provided. In this embodiment, theconfiguration of the grinding chamber 412' changes in a man ner optimumto the grinding operation.

The manner of altering the configuration of the grinding chamber 412'will now be described with reference to FlGS. 17-20. FIG. 17 illustratesthe state from which both the rotor blade 411 and the movable casing 413are going to rotate, namely the starting positions of the blade 4]] andcasing 413. The perigee P, is the point at which the rotor bladeapproaches the inner face of the movable casing 413 at the closestdistance, while the apogee P is the position farthest from the innerface of the movable casing 413. Subsequently, as illustrated in FIG. 18,when the rotor blade 41] and the rotatable casing 413 rotate one-fourthof a revolution in directions opposite to each other, contrary to thestarting state shown in FIG. 17, the perigee P, is now at the pointfarthest from the inner face ofthe movable casing 413 while the apogee Pis now at the point nearest thereto, due to the fact that the casing 413is eccentrically offset relative to the rotor blade. When the rotorblade 4]] and movable casing 413 ro tate another one-fourth ofarevolution, as illustrated in FIG. 19, the positional relationshipbetween P, and P is similar to that observed at the starting positions,and when they rotate still another one-fourth revolution, the positionalrelationship between P, and P is similar to that observed when theyrotate one-fourth of a revolution from the starting positions, asillustrated in FIG, 20.

Thus, in the instance that the rotor blade 411 and movable casing 413are rotated in reverse directions with a deviation ofd provided betweentheir centers of rotation O, and 0 respectively, the perigee and apogeepoints P, and P of the rotor blade 411, and points A, B, C and D uponthe inner face ofthe moving casing 413, change their relative positionsas the same are rotated, as shown in FIGS. [7-20, whereby the points P,and P approach the inner face of the movable casing 413, twice duringone rotation, and consequently the chipped clearance is successivelychanged within a range of L, to L and the above-mentioned effectsattained by this invention can be further enhanced.

Furthermore, the grinding chambers formed upon both sides of the rotorblade 411 change their configurations both longitudinally and laterallyand the move ment thereby imparted to the rubber material can be quitevigorous. In this embodiment of this invention, if the rotationalfrequency F, of the rotor blade 41 I is different from the rotationalfrequency F of the movable casing 413, i.e., if the ratio of F F isadjusted to l 1 +3, the points at which P, and P approach the inner faceof the movable casing 413 are variable and they are successivelydeviated from one another in corre spondence to the difference in therotational frequency between the rotor blade 411 and movable casing 413,whereby the grinding work can be made uniform.

As described above, in this invention the rotor shaft is rotated in aparticular manner so that the chipped clearance within the grindingchamber is changed during rotation. As a result of this specificstructure, even if the rubber material is elastically deformed andcaught between the rotor blade and the inner wall of the grindingchamber, the condition of the rubber material is immediately andautomatically altered and the rubber material can be acted upon bydifferent forces with the result that stagnation of the rubber materialand partial abrasion or heat generation can be effectively prevented,and the rubber material can be positively cut and sheared while reducingthe load imposed upon the rotor shaft. Moreover, since the volume of thegrinding chamber is altered during rotation, crushing forces are imposedupon the rubber material as well as cutting and shearing forces.

Accordingly, in this invention, even a vulcanized rub her or rubberproduct having a high degree of elasticity can be ground smoothly andeasily and at a high rate of efficiency. Furthermore, if a suitablenumber of concave portions are formed upon the inner wall of the movablecasing as illustrated in FIGS. 12 and 13, it is possible to enhance theabove effects by employing an apparatus having a relatively simplestructure. Still further, if the rotor blade and movable casing arerotated under eccentric conditions, as illustrated in FIGS. 14 and 16-20it is possible to alter the chipped clearance in a non-stepped mannerand the above-mentioned crushing forces imparted to the rubber materialcan be greatly enhanced so as to conduct the grinding operation stillmore effectively.

Obviously, many modifications and variations of the present inventionare possible in light of the above teachings. It is to be understoodtherefore that within the scope of the appended claims the presentinvention may be practiced otherwise than as specifically describedherein What is claimed as new and desired to be secured by LettersPatent of the United States is:

1. An apparatus for pulverizing rubber materials such as vulcanizedrubber and rubber products, which comprises:

a rotor having an egg-shaped cross-section:

a casing surrounding said rotor;

drive means for rotating said rotor relative to said casing; and

clearance-changing means for changing the clearance formed between theouter periphery of said rotor and the inner wall of said casing as saidrotor rotates, said clearance-changing means includes an inner wall ofnon-circular cross-section disposed within said casing.

2. An apparatus as set forth in claim 1, wherein said drive meansfurther comprises a mechanism for rotating said casing in a directionopposite to the direction of rotation of said rotor.

1. An apparatus for pulverizing rubber materials such as vulcanizedrubber and rubber products, which comprises: a rotor having anegg-shaped cross-section; a casing surrounding said rotor; drive meansfor rotating said rotor relative to said casing; and clearance-changingmeans for changing the clearance formed between the outer periphery ofsaid rotor and the inner wall of said casing as said rotor rotates, saidclearance-changing means includes an inner wall of non-circularcross-section disposed within said casing.
 2. An apparatus as set forthin claim 1, wherein said drive means further comprises a mechanism forrotating said casing in a direction opposite to the direction ofrotation of said rotor.